3478
A. L. HENNE,A. M. WHALEY AND J. K. STEVENSON
NO. 9 from CClZ=CFCFa to CClF=CFCClFZ or possibly CClzFCF=CFz No. 10 from CClzBrCFBrCFa t o CClFBrCFBrCClFZ or possibly CClzFCFBrCFzBr
Summary A corrected representation of the stepwise ac-
[CONTRIBUTION FROM
THE
VOl. 63
tion of antimony trifluoride on CHCI2CCl2CCl3is CHChCCl2CC12F + CHClzCC12CClF2 + CHC12CClFCClFz CHClFCClFCClF2. Physical properties of CHC1FCC1FCClF2,CC1,FCCIFCCIF2, and CClsCClFCF3 are tabulated. --+
COLUMBUS, OHIO
RECEIVED AUGUST11, 1941
DEPARTMENT OF CHEMISTRY AT THEOHIOSTATE UNIVERSITY
A New Method of Synthesizing Organic 1,1, I-Trifluorides BY ALBERTL. HENNE,ATHERTON M. WHALEYAND JAMES K. STEVENSON
The origin of the present work is the discovery reaction occurs almost quantitatively, while the that hexachloropropylene, CC12=CCICCL, heated second one gives only 60% yields and is accomwith antimony trifluoride without the usual salt panied by extensive decomposition. The strucof pentavalent antimony as a “fluorine carrier,’’ ture resemblance of the reagents is best illustrated is easily and completely transformed into CC&= by their developed formulas. CClCF3. The novel features of this re- CH-cH=C-cCls RR,C-c-cCls C1*C=C-CCls I action are: (1) substitution proceeds 11 I I RU c1 smoothly and rapidly; (2) no salt of Benzotrichloride + General formula +Hexachloropropylene pentavalent antimony is needed or wanted as a “fluorine carrier”; (3) a -CF3 group The olefinic compounds prepared, together with is generated where antimony fluoride was expected such of their dichlorides as are new, are listed in to substitute only two halogen atoms and to create Table I. The compound CF2=CClCF3, which was a -CClF2 group. It is concluded that substitu- too volatile to be handled conveniently, was imtion of fluorine for chlorine is facilitated and made mediately transformed into its dichloride, CF2more complete because the three replaceable halo- ClCC12CFz. The compound CCI2=CFCF3 was gen atoms are linked to a carbon atom once re- transformed into its dichloride a t once, lest the moved from a double bond, and can therefore be small amount prepared be lost during its purification. The compound CC12=CHCF3 was preregarded as “allylic” in nature. In order to establish the generality of the pared on a very small scale. All dichlorides were method as well as its limitations, the following thoroughly purified and analyzed. In Table I, M R , is the molecular refraction caladditional experiments were performed : (1) CF2 culated by means of the Lorentz-Lorenz formula. =CClCCIF2 was transformed into CF-CClCFa, (2) CHC1=CC1CC13 into CHCl=CCICF3, (3) A R p is the atomic refraction for fluorine, obtained CCl-CFCCI, into CClFCFCF8, (4) C C l d H - by subtracting from M R the generally accepted CCla into CC12=CHCFa. In contrast, it was increments for C (2.418), H ( l . l O O ) , C1 (5.967) found impossible to replace the chlorine by fluo- and double bond (1.733). Chlorine analyses are reported for all comrine in CH2=CHCC13 and the reagents were repounds which could be handled conveniently; covered unaffected. In the case of CH2=CHCH2C1, extensive decomposition occurred and no re- when this was impractical, the chlorine analysis of action product was obtained. These experiments their dichlorides is given. Fluorine analyses, were interpreted as an indication that the doubly which are difficult and tedious, were performed a t linked carbon atoms must bear some halogen crucial points only. In general, the analytical results have a tendency to be slightly low, and this is atoms. There is a strong experimental resemblance be- attributed to the great difficulty of obtaining a complete decomposition of these extremely stable tween the synthesis of CC12=CCICF3 from CC12= CClCC13 and that of C6HbCFs from CaHaCCla. compounds. The results are listed in Table 11. The position in which the fluorine atoms enter Both occur very fast and take place by heating the organic chloride with antimony trifluoride to the molecule is demonstrated by the fact that 125-140”. The only difference is that the first identical samples of CC13CC1&F3 were obtained CH-cHI=CH
3479
SYNTHESIS OF ORGANIC 1,~,~-TRIFLUORIDES
Dec., 1041
TABLE I PHYSICAL PROPERTIES Name
CClz===CClCCl*F CClz=CClCClFI C C+C C1CFa CClaCClzCFs CFz=CClCFzCl CFz=CClCFs CF2ClCClZCFa CClz==CFCFa CClsCClFCFa CH Cl=C ClCFa CClz=CHCFa
F. p . , "C.
B. p . . 'C.
d 204
MRD
ARP
Glass -103.0 -114.7 f109.1 -121.2 -130.4 - 4.30
170.2 128.0 88.3 153.1 44.7 6.8 72.0 46.0 112.4 53.7 54.5
1.7041 1.6598 1.6188
1.5050 1.4573 1,4095
40.43 35.43 30.48
1.60 1.29 1.20
1.5106
1.3484
25.45
1.13
1.3519 1.6681 (approximate) 1.4002 1.7254 1.4653 1.3670 .. 1.3688
30.77
1.12
..
+ 12.1
- 109.23
TABLE I1 ANALYSES Name
CClZ=CClCClzF CClZ=CClCClFz CClz=CClCFa CCljCClzCFa CFz=CClCFzCI CFzClCClzCFa CC13CClFCFa CHCl=CClCFa
yo Chlorine Calcd. Found
76.3 65.7 53.3 65.7 38.8 44.8 55.9 43.0
75.6 65.5 53.3 65.6 38.7 44.4 55.5 42.6
yo Fluorine Calcd. Found
28.6
28.3
40.0 29.9
40.0 29.1
by two different sequences of reaction, thus: (1) CC12=CCICC13 + CCIz=CCICF3 + CClaCC1-zCF3and ( 2 ) CH3CHzCC13 + CHsCHzCF3 + Cc&CCl2CFa. Samples of CFZCICCIZCF~ prepared in two different ways were also found to be identical: (1) CF2=CCICFZC1 -+ CFZ=CCICF~ --j CFzCICClzCFRand (2) CH3CHzCFa+ CClaCCl2CF3 + C F ~ C I C C I Z C F ~ . ~ Experimental The substitutions of fluorine for chlorine were performed by experiments analogous to the following. Preparation of CCl-CClCFa.-Four moles of CCICClCCla and six moles of finely ground antimony trifluoride were placed in a metal container surmounted by a one meter length of pipe to act as dephlegmator. The top of the pipe was fitted with a thermometer well, and delivered into a metal, water-cooled downward condenser. The container was placed in an oil-bath which had been heated t o 150'. The purpose of this was to carry out the reaction as quickly as possible, because this procedure minimizes decomposition. The reaction started promptly, and the reaction product distilled rapidly at 90-105". When the distillation slowed down, the oil-bath was removed, and the reaction vessel heated with a free flame until all the organic material had been removed. The distillate was steam distilled, dried, and rectified to give 43y0 (1) A. M Whaley, Dissertation, The Ohio State University, 1941 ( 2 ) James K . Stevenson. M.S. Thesis, The Ohio State University, 1942.
.. ..
N*D
..
..
.. ..
.. ..
..
..
35.69 25.27
1.14 1.08
..
..
of CCl-CClCFs (b. p. SS'), 28% of CClFCClCClFZ (b. p. 12S0), 13% of CC11=CClCCI~F(b. p. 170°), and 10% of recovered CClFCClCCl,. Preparation of CFz=CClCFa.--The starting material, CF1=CC1CF2C1, was obtained quantitatively by a treatment of CFnCICCl&!FzCla with zinc in absolute alcohol. One-half a mole of this material was placed in a steel container together with 0.3 mole of ground antimony fluoride. The container was surmounted by a metal pipe bearing a pressure gage and a releasing needle valve. The whole equipment was tested beforehand to withstand a working pressure of forty atmospherzs. The reaction vessel was heated to 200' in an oil-bath. The pressure rose progressively to 18 atmospheres, then rapidly to about 23 atmospheres. The oil-bath was removed and the reaction vessel allowed to cool to room temperature. The needle valve was opened and the CFFCClCFs (b. p. 7') was allowed to distill into a receiver cooled with dry-ice. The valve was closed, the vessel heated again to 200' and tapped intermittently until the pressure no longer rose. At this point, the unreacted material was allowed to distill to be recovered. The yields of repurified product were 47% of CF8= CClCFa (b. p. 7'), and 15% of recovered CFFCClCF2Cl Handling losses were relatively large on (b. p. 45'). account of the small amount of material used, its low boiling point, and the high temperature prevailing in the laboratory during the operations. Preparation of CFZCICC~ZCF~.-CFFCC~CF~was placed in a flask surmounted by a dry-ice reflux condenser. Chlorine was bubbled through the liquid, part of it adding readily. An excess of chlorine was introduced into the liquid, and the mixture was allowed to reflux in strong sunlight for two hours. After removal of the excess of chlorine, CFaClCC12CFa (b. p. 72") was obtained quantitatively.
Summary A -CCla group once removed from a double bond is rapidly and quantitatively transformed into a -CClzF, -CCIFz or -CF8 group by halogen interchange with antimony trifluoride, in the absence of the usual catalyst. COLUMBUS, OHIO
RECEIVED OCTOBER 3, 1941
(3) H e m e and Renoll. THISJOURNAL, 61, 2489 (1939).
